The subject matter disclosed herein relates to non-invasive imaging and, in particular, to correcting or reducing artifacts in the image reconstruction process.
In the fields of medical imaging, animal imaging, quality control and security screening, non-invasive imaging techniques have gained importance due to benefits that include unobtrusiveness, convenience, and speed. In medical and research contexts, non-invasive imaging techniques are used to image organs or tissues beneath the surface of the skin. Similarly, in industrial or quality control (QC) contexts, non-invasive imaging techniques are used to examine parts or items for hidden defects that may not be evident from an external examination. In security screening, non-invasive imaging techniques are typically used to examine the contents of containers (e.g., packages, bags, or luggage) without opening the containers and/or to screen individuals entering or leaving a secure location.
A number of non-invasive imaging modalities exist today. A particular modality may be selected based upon the imaging context, such as the organ or tissue to be imaged, the spatial and/or temporal resolution desired, or upon whether structural or functional characteristics are of interest. One type of imaging modality is computed tomography (CT) in which X-ray attenuation data is collected at different angular positions relative to the subject or object undergoing imaging. The collected data is reconstructed to generate three-dimensional representations of the subject or object undergoing imaging, including those internal structures not typically visible in an external examination. One technique by which image data may be reconstructed is iterative reconstruction, which may be utilized when it is desired to optimize image quality and minimize patient dose.
However, the iterative reconstruction process may be susceptible to various undesired image artifacts in the generated image. These artifacts may arise from a number of sources, including motion of or within the subject being imaged, data inconsistencies introduced by the scan protocol, and/or data inconsistencies introduced by the reconstruction technique. The artifacts may degrade the image quality and/or reduce the usefulness of the images. However, even if the artifacts do not reduce the usefulness of the images, their presence is still typically undesirable as they detract from the image quality. In some instances, iterative reconstruction methods may be as or more susceptible to such artifacts than direct reconstruction techniques, such as filtered backprojection (FBP).